Northern Lights

Northen Lights, originally uploaded by jonrr.

Scientists have found what causes the Northern Lights.

Writing in the journal Science, the scientists said on Thursday that explosions of magnetic energy occurring a third of the way between Earth and the moon drive the sudden brightening of the Northern Lights and Southern Lights.[...]

Auroral displays are associated with the solar wind -- electrically charged particles continuously spewing outward from the sun. Earth's magnetic field lines reach far out into space as they store energy from the solar wind.

The researchers said that as two magnetic field lines come close together due to the storage of energy from the sun, a critical limit is reached and the lines reconnect, causing magnetic energy to be turned into kinetic energy and heat. The release of this energy sparks the auroral flare-ups.